1. Field of the Invention
This invention relates to a pressure relief valve capable of regulating the flow of fluid from a point of use to atmosphere at a predetermined rate by the direction of the fluid flow path from its point of use through at least one metered aperture or port assembly.
2. Description of the Prior Art
In modern medical practice the monitoring of blood pressure is an extremely common and well established practice. More specifically, with relatively recent medical developments relating to the control of unnecessarily high blood pressure of a patient, there has been a movement to urge affected members of the population to obtain facilities for measuring their own blood pressure.
In application, a pressure cuff or sleeve is placed in substantially surrounding relation to the arm somewhat in spaced relation above the elbow. The pressure cuff is pressurized through the application of air, under pressure, to a bladder or like structure contained within the pressure cuff. Pressure is generally applied by means of a hand manipulated squeeze bulb structured with a one-way valve so as to direct air or like fluid under pressure from the bulb to the bladder of the pressure sleeve as set forth above. A sphygmomanometer head is interconnected in fluid communication to the cuff for the purpose of measuring the arterial and venous pressure of the patient. Both systolic and diastolic pressures are determined through listening through the stethoscope to the pulse, or otherwise monitoring, as the pressure is released in a regulated fashion from the cuff. This release of pressure conventionally is accomplished through a simplified release valve in the form of a threaded connector. In operation, rotation of the threaded connector to its open position serves to vent the pressurized fluid from the pressure cuff. The rate of fluid flow and pressure release is determined by the amount of removal of the threaded connector or valve element from the remaining valve assembly.
In the most popular prior art devices, such release cannot be controlled within specified limits thereby resulting in irregular rates of flow or release of pressure during the measurement of the blood pressure and the observance of the sphyg head.
The sphyg head presents visual indication of the respective systolic and diastolic pressures as indicated thereon by coordinating recognizable sounds or changes in the audio or other report of the pulse. In that audio or other method of detection of this pulse is dependent upon the rate of release of the pressure or air flow from the pressurized cuff, the operator of the sphygmomanometer observes operation of the sphyg head at different rates. This non-uniform performance of the sphyg head again, due to the erratic rate of fluid flow from the pressurized cuff, frequently results in multiple performances of the entire monitoring process in order to obtain an accurate, reliable measurement of arterial pressure.
Accordingly, it can be readily seen that it would be highly desirable to accomplish a standard rate of fluid flow of the pressurized air or fluid from the pressure cuff during the observance of the sphyg head. Greater accuracy and efficiency would result in standard rates of release of the pressure from the pressurized cuff.
Accordingly, there is a great need in the medical profession for a valve structure being of relatively simple design and capable of efficiently and effectively releasing fluid from the pressure cuff at an adjustable, consistent rate.